Melting chocolate yesterday, made us think of M&Ms, and their claim to "melt in your mouth, and not in your hands". Naturally, we had to check out the validity of the claim.
We cut open an M&M, and observed the thin candy coating around the chocolate center. Then, we placed the M&M with a few others into a bowl...
...and used a blow dryer to heat the M&Ms, keeping track of the temperature with a candy thermometer.
At around 100 degrees Fahrenheit (we were aiming for body temperature - the temperature an M&M would be at in your hand, but it's difficult to be accurate with a blow dryer), we poked the chocolate with a toothpick. It was melted, but the candy shell was not.
In fact, the candy shell did not melt even when we increased the temperature (by moving the blow dryer closer to the bowl) to 200 degrees Fahrenheit, the temperature at which we found a Lifesaver candy would begin to melt.
Clearly, the heat of your hand will not melt the candy shell of an M&M. Rather than melt, the candy coating dissolves when it comes in contact with moisture (which is why if you have sweaty hands, all bets are off).
To check our thinking, we poured a small amount of cold water (we were curious to see if temperature mattered) in a bowl of fresh M&Ms.
The candy shells started to dissolve immediately.
Finally, we poured enough water into the bowl to completely cover the candies, so we could watch the edible M stickers float to the top, which is pretty cool!
It's great to be a homeschooler.